Bloom naturally happens in irl firearms too, more so in free floating barrels. The barrel does changes shape with every shot in full auto. Its very minor and almost unnoticeable but it does happen. The issue here is that the per bullet formula is no more. In previous titles each bullet type would have the exact same characteristics that would then be modified by barrel length and ROF and such. In this title it seems each weapon is tuned individually regardless of chambering in such a way that devs can give an appearance that the over abundance if accessories serve a purpose greater than just cosmetics.
Personally I wouldnt care if nothing unlocked for several levels if when something did it had a noticeable improvement in performance instead of trying to balance points, buffs, and nerfs that create required attachments for every weapon regardless of class.